He said he stopped the practice, gave up his recreational hunting trips and surrendered all the weapons he owned after the 1996 massacre claimed the lives of 35 people in Tasmania.

The former army officer said he was the victim of a long-running smear campaign in his Rockhampton electorate, that's also seen him falsely accused of firing a gun during a dispute with his wife.

"I occasionally used firearms to dispose of vermin from residential properties at various times," he said in a statement on Monday.

"But Port Arthur changed all that. I was so disturbed by Port Arthur I disposed of my weapons immediately."

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News Corp reported the Opposition would write to the police commissioner, asking him to consider whether Mr Byrne broke the law by firing his .22 calibre rifle at rats in the roof cavity of his house in suburban Rockhampton.

The Weapons Act restricts recreational licence holders to shooting on rural land with the owner's approval, while those with a club licence can only fire a weapon at a shooting range.

The Opposition said the premier must stand the minister aside while police investigate what gun licence Mr Byrne held at the time.

Premier Annastacia Palaszczuk stood by Mr Byrne, saying firing a weapon at home was legal and any offence would be outdated anyway.

Queensland Shooters Union president Graham Park said the now minister may have committed an offence under the Weapons Act.

"This is why we are always trying to work with the government, so we can streamline legislation so police resources aren't used on things like mouse shootings," he told the paper.

He said other Queenslanders should turn to baits, not bullets, if they had rodent problems.